The present invention relates to a new rotary switch mechanism that employs a reduced number of operational components as compared to the prior art. More specifically, this invention relates to an improved rotary switch mechanism that is formed from a thin metallic material and is selectibly operable using a magnet.
The prior art provides various types of multiple position rotary switches for use in connection with electrical devices. One example of a prior art multiple position rotary switch may be found in Erickson, et al., U.S. Pat. No. 4,131,771. The Erickson, et al. switch includes a switch body shaped like a wheel attached to the end of a shaft. The wheel is mounted within a housing between a pair of circuit boards. A spring loaded detent in the wall of the housing engages serrations provided along the outer diameter of the wheel in order to provide tactile feed back and retain the wheel in the desired preset positions that operate the switch functions. The top and bottom of the wheel each include a plurality of brushes that contact pads that correspond to circuit traces formed on the circuit boards as the shaft rotates the wheel. During assembly of the switch, after the circuit boards are properly aligned with the wheel sandwiched therebetween, pins in the housing are melted in order to permanently secure the boards in position relative to one another and the wheel orientation. As the wheel is rotated, the brushes align with contact pads on the circuit boards thereby energizing the corresponding circuits. This type of configuration however is comparatively bulky and requires a great deal of space within a compact electronic device. Further, because of the brush style contacts, the potential for failure of the contacts is high.
Another example of a prior art switch may be found in the Model 77 Multimeter produced by John Fluke Mfg., Co., Inc. of Everett, Wash. The switch utilized in this device comprises a circular non-conductive stationary disk having a plurality of posts mounted on each of its major surfaces. A smaller rotatable disk is provided in the center of the stationary disk. Each side of the rotatable disk includes a pair of contacts that serve to complete connections between the posts located on each side of the stationary disk as the rotational disk is rotated. The posts are electrically connected to the main circuit board of the device and are permanently held in position upon the stationary disk by rivets.
The prior art further provides an electrical device distributed by the Actron Manufacturing Company. The electrical device includes a switch mechanism having a race that is integrally formed into the top cover of the electrical device. The top cover includes an opening through which a portion of the knob of the switch mechanism extends. The race extends around the entire diameter of the opening along the inside surface of the top cover. The knob is retained within the opening by a circuit board that is mounted to the top cover such that a portion of the knob is sandwiched between the circuit board and the race. The circuit board includes both the circuit traces, which serve to electrically interconnect the electrical components mounted upon the board and the switching circuit, which provides the electronic switching functions for the device. The race includes a plurality of spaced arcuate protrusions that form multiple peaks and valleys along the race. The knob comprises a cylindrical disk having on one surface a handle and at the opposite surface a protruding rim. The rim includes a first and second pair of diametrically opposed upstanding platforms. The first platforms are of sufficient size that rotation of the knob, the first pair of platforms glide along the peaks of the protrusions. The second platforms each include a socket for receiving a spring and a ball bearing. The bearing is located on top of the spring such that the ball bearing is sandwiched between the spring and the race. The spring provides a biasing force that retains the bearing against the race such that as the knob is rotated, the bearing aligns itself in the valleys of the race thereby mechanically stabilizing the knob in preselected positions. Between the preselected positions, the bearing is received within the socket so as to allow the bearing to slide over the top or peaks of the protrusions. The knob includes along its opposite end a plurality of wiping members that rotate with the knob and contact the switching circuit thereby selectively closing the switching circuit as the knob is rotated to preselected positions. In this electrical device, again brushes or wipers are included causing constant rubbing of the switching elements during operation of the switch of the changing of the switch orientation.
As an attempt to eliminate the need for brushes and to reduce the constant movement of the contact elements within the switch, multifunctional switching in compact spaces is often accomplished using reed switches. To actuate the switch a magnetic force is applied near the switch moving an actuator arm into contact with a secondary contact arm thereby greatly reducing the operational range of movement of the device. These devices however have a significant dimensional component in all three dimensions. In addition, as a function of the way in which they are constructed, a magnetic force applied proximate to the switch from any direction could potentially operate the switch. This is an undesirable feature in flashlight construction where an external magnet in the proximity of the flashlight may cause it to operate or even malfunction. Reed switches are also quite fragile and care must be taken in handling the component when assembling it into the overall flashlight assembly so as not to damage the operation of the device resulting in a defective end product. This problem is amplified where the desired end product requires a multi-function capability, thus requiring several individual reed switches to be installed to create the multifunctional relationship. Finally, because reed switches are complex they are costly to manufacture thus increasing the cost of the end product.
There is therefore a need for a simple, compact device that has limited moving components, that is rugged and that is capable of multifunctional switching. In addition, there is a need for a cost effective alternative to reed switches that provide a compact multifunctional switching solution.
In this regard, in accordance with the present invention, a novel construction for a multifunctional rotary switching device is provided. The body of the switch includes a radial array of switching contact arms, each arm being connected at one end to a central hub. The switch is preferably stamped from a thin sheet of flexible metallic material having magnetic characteristics. The metallic material has a sufficient thickness dimension that causes the material to have an internal spring bias causing the arms of the switch to remain in a normally flat position, i.e. the arms stay normally aligned with the plane of the central hub. Each of the contact arms of the switch, on the end opposite the hub, may have an increased width dimension (bump or shoulder) to provide an enlarged contact area wherein the switch arm contacts the respective switch circuit traces as shown in the drawings.
The switch of the present invention is then installed onto a printed circuit board switching substrate in the preferred embodiment. The central hub of the switch is rigidly connected to the switching substrate and an electrical connection is made thereto, providing a common electrical connection to each of the switching arms. On the switching substrate, at locations that correspond to the contact end of each of the switching arms, is a contact pad that the contact end of each arm comes into contact with in the relaxed, normally closed state. Further, a magnet is installed into a rotatable actuator in close proximity to the surface of the switch of the present invention. The magnetic force of the magnet mounted in the actuator lifts the contact arm of the switch over which the magnet is aligned. In this position, the magnet opens the corresponding contact arm of the switch.
A microprocessor device is provided on the switching substrate that periodically samples the electrical contact at each of the contact pads of the switch. Upon the opening of one of the normally closed contacts, the microprocessor senses the open circuit and performs an instruction that corresponds to that contact being open.
A second embodiment of the switch of the present invention provides for a switch that has the contact arms bent at a perpendicular angle to the central hub. This embodiment creates a cup shaped switch configuration that can be installed into the barrel of a cylindrical flashlight handle.
Accordingly, one of the objects of the present invention is the provision of a rotatable, multi-function switch that has enhanced functioning. Another object of the present invention is the provision of a compact, lightweight, low cost rotary switch mechanism having a reduced number of operational components. Yet another object of the present invention is the provision of a compact rotary, multi-function switch mechanism that is easily manufactured and assembled from low cost components. A further object of the present invention is the provision of a rotary switch that has operating characteristics that allow the device to be installed in either a flat or tubular configuration using the same operational components.